Women's Health investigates the surprising reasons why the most dedicated exercisers are also some of the biggest drinkers

No, this isn't the beginning of a tired joke, it's an increasingly common real-life occurrence. And research shows that, once inside, those avid runners—and other frequent exercisers—tend to accrue bigger tabs than the average bar patron. Picture the Cheers gang clad in head-to-toe sweat-wicking spandex.

A 2009 study from the University of Miami found that the more people exercise, the more they drink—with the most active women consuming the highest amounts every month. It's a peculiar phenomenon that has had scientists scratching their heads since 1990, when research first pinpointed the alcohol-exercise connection. But they expected that, at some point, the script would be flipped—that the biggest boozers would exercise less. Never happened.

Instead, this landmark 2009 analysis of more than 230,000 men and women revealed that, on average, drinkers of both genders and all ages (not just wild twentysomethings) were 10 percent more likely to engage in vigorous exercise like running. Heavy drinkers exercised 10 minutes more each week than moderate drinkers and 20 minutes more than abstainers. An extra bender actually increased the number of minutes of total and vigorous exercise the men and women did that week.

"There's this misconception that heavy drinkers are exercise-averse couch potatoes," explains study author Michael T. French, Ph.D., a professor of health economics at the University of Miami. "That may be true in some cases, but that's certainly not what we've found."

This trend seems particularly pronounced in women—especially active, educated women, who, according to recent research from Columbia University's Mailman School of Public Health, are drinking more than ever. In part, progress may be the root of this evil: With growing numbers of women in the workplace and other male-dominated arenas, it has become increasingly socially acceptable for women to go out and belly up to the bar alongside their male counterparts—and to overdo it.

Working Out to Work It Off
One simple theory scientists have to support the drinking-exercise connection is the morning-after phenomenon. In this case, the party girl who downs a few appletinis (and maybe some mozzarella sticks) feels the need to repent for those calories by banging out five or six miles the next morning.

"Women who consume alcohol could simply be exercising more to burn it off and avoid weight gain," says French. "Likewise, they may drink more simply because they can, as they know they're burning calories, so they're less worried about the weight gain."

But exercising to atone for the sins of the night before doesn't explain why someone would chase an indoor cycling class with a round of drinks, which also happens with staggering frequency. This, researchers say, could be the product of a "work hard, play hard" personality type. "There are people who are sensation seekers," says Ana M. Abrantes, Ph.D., an assistant professor at Brown University's Alpert Medical School. "They engage in activities that produce intense sensations and can be quickly bored by things that don't produce those feelings."

For others, it might be a matter of blowing off stress. Which may be why some women offset their tension with a boot-camp class, or by getting loaded, or both. "Exercising stimulates the release of serotonin, which is your natural antidepressant, as well as dopamine, which is the primary neurotransmitter in your brain's reward center. It makes us feel good," says brain chemistry researcher J. David Glass, Ph.D., a professor at Kent State University. Alcohol has a similar effect—hence, the buzz you get soothes your worries (if only temporarily).

The Pleasure Principle
The downside of constantly activating these reward pathways is this: Your brain gets used to it and wants more, says Brian R. Christie, Ph.D., neuroscience program director at the University of British Columbia Division of Medical Sciences. So it's not shocking that someone who craves a 10-K or a blistering CrossFit session will also readily down a couple of vodka sodas.

Animal studies bear out this effect. In a 2010 study, University of Houston scientists took a group of alcohol-loving rats and gave half of them running wheels while the other half stayed sedentary for three weeks. Then they took away the wheels and granted half the rodents in each group an open bar, suspecting that the fit rats would drink less than the lazy ones. Wrong. They drank more.

Associate professor of psychology and study author J. Leigh Leasure, Ph.D., was surprised—until she saw the epidemiological research, such as the aforementioned landmark human study. She began to look at what was going on in the brain. "We found that rats that exercised before drinking alcohol needed to consume more than sedentary rats to show the same signs of intoxication," she says.

In short, the rats needed more booze to get buzzed, which could explain some things about human behavior. "Since alcohol enhances the activity of the brain's opioid system, it's possible that exercise could cause cross-tolerance to alcohol—meaning, it may make alcohol less rewarding, so people would therefore drink more of it in order to get its feel-good effects," says Leasure.

Interestingly, Glass's research found that, in moderation, exercise and alcohol may replace one another as a means to the feel-good end, allowing people to swap a natural, healthy high (exercise) for a potentially harmful one (alcohol). But that goes out the window when you start bingeing, which you might do when the usual drink or two doesn't budge your reward meter after a sweat session.

Your Health, on the Rocks
Theoretically, there's a perk to the exercise-drinking connection: Excessive swilling can lead to apoptosis, or cell death in the brain. Sweat sessions, on the other hand, dramatically increase neurotrophin production so you can make new brain cells, says Christie. One exercise by-product: super-fertilizer for the brain that doubles and triples neurons and leads to better cognitive functioning.

That said, don't be fooled into thinking your daily trip to the gym gives you a free pass at the bar. Being fit can make you feel impervious to the ill effects of drinking, such as liver disease, diabetes, and certain cancers, and even trick you into thinking that you could never turn into an alcoholic. But as it turns out, that same Columbia University survey found that more women are becoming alcoholics. And as a woman, you're particularly vulnerable to the very real (and physical) risks of overdoing it.

For one, women have proportionately more body fat and less water, so they don't absorb or dilute alcohol as well as men do. They also have a lower concentration of dehydrogenase, the primary enzyme that breaks down alcohol in the body. Women's fluctuating hormones make matters worse, since estrogen affects alcohol metabolism. That's why one drink might give you a slight buzz one night and slam you a few weeks later.

Women also fall victim to alcohol-related illnesses more easily. They're more likely to develop liver disorders and are more prone than men to alcohol-related brain and heart damage. Alcohol also increases their chance of getting breast cancer. And excessive alcohol consumption can lead to all of these no matter how much you exercise, says Tavis Piattoly, R.D., a sports dietitian for Tulane University athletics.

On a less dire note, too much booze is also just plain bad for your exercise performance. Drinking five or more drinks on any one occasion affects the brain and body for several days. Even lesser amounts, especially in women, can hurt your fitness on nearly every level. (For more, see How Alcohol Affects Your Body.)

How Much Is Too Much?
Nobody is saying to turn off the tap completely. Moderate alcohol consumption (two drinks a day for guys, one for women) is linked to longevity. Some experts tended to lean a little more liberally, though. "I tell my clients, 'Have a plan and limit yourself,'" says Piattoly. "For women, I'd say don't have more than three—and in between every drink, have water, which keeps you hydrated and slows down the alcohol intake."

The warning signs that you (or a friend) are in trouble are the same whether the problem behavior is extreme exercise or consumption, says Abrantes. "If you're spending a lot of time doing either and not fulfilling work and personal responsibilities; if you need to do more of the behavior to get the same effect; if you feel very irritable when you can't engage in the behavior, there's a problem," she says. In a nutshell: If you have to ask, there's probably a problem.

When you do go on a bender, follow it with a few dry days to give your body a rest. "If you only occasionally go overboard, then taking a few days off is a good way to let your stomach lining heal, so you can absorb all the nutrients you need from food as well as restore a healthy sleep pattern and generally help your body recover," says Christie. You may also want to try yoga. Research shows that practicing it may help raise your brain's GABA levels, which also helps lift depression and reduce anxiety—without the hangover. Says Christie: "It might be an effective way to reduce the cravings for less-healthy stress relievers."

BEYOND BOOZING
Three more unhealthy habits of exercisers

They Have Risky Sex
Compared with nonathletes, athletes are more likely to drink before or during sex (a dicey sex behavior).
Source: Journal of Studies on and Drugs

They Dabble in Eating Disorders
Twenty-four percent of women competing in endurance sports display dangerous eating behaviors such as bingeing and purging, versus 9 to 10 percent of women in the general population.
Source: Clinical Journal of Sport Medicine

They Get Burned
Despite being more vulnerable to skin cancer than the average person, 85 percent of college athletes reported not using sunscreen in the past week.
Source: Journal of the American Academy of Dermatology